JP2010116924A - Cylinder liner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder liner capable of restraining the temperature of a cylinder from becoming excessively low. <P>SOLUTION: A coating film 5 having heat conductivity lower than a cylinder block 11 and the cylinder liner 2, is formed only in a range up to the lower end from an intermediate part in the axial direction among an outer peripheral surface of the cylinder liner 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an engine cylinder liner.

  An engine cylinder block having a cylinder liner has been put into practical use. As the cylinder liner, for example, one described in Patent Document 1 is known.

Japanese Utility Model Publication No. 53-163405

  In recent years, the engine is required to further improve the fuel consumption rate in consideration of the environment and the like. On the other hand, when there is a part where the cylinder temperature is significantly lower than the appropriate temperature during engine operation, the viscosity of the engine oil in the surrounding area becomes excessively high, so the fuel consumption rate increases as the friction increases. It has been confirmed that it will worsen. Such deterioration of the fuel consumption rate due to the temperature of the cylinder appears more prominently in an engine in which the thermal conductivity of the cylinder block is relatively large (for example, an engine made of an aluminum alloy).

  This invention is made | formed in view of such a situation, The objective is to provide the cylinder liner which can suppress that the temperature of a cylinder becomes low too much.

In the following, means for achieving the above object and its effects are described.
(1) According to the first aspect of the present invention, in the cast-in cylinder liner applied to the cylinder block, a coating having a thermal conductivity smaller than at least one of the cylinder block and the cylinder liner is applied to the outer peripheral surface of the cylinder liner. The gist is that it is formed only in the range from the middle part in the axial direction to the lower end.

  According to the above invention, since the cylinder liner and the cylinder block are joined through the low thermal conductivity film, the thermal conductivity between the cylinder block and the cylinder liner is lowered. Thereby, since the temperature of a cylinder rises, it becomes possible to suppress that the temperature of a cylinder becomes too low.

(2) The invention according to claim 2 is characterized in that, in the cylinder liner according to claim 1, the thickness of the coating is increased toward the lower end in the axial direction.
According to the above invention, since the thermal conductivity between the cylinder block and the cylinder liner is increased toward the lower end of the cylinder, the temperature difference in the axial direction of the cylinder can be reduced.

  (3) The invention according to claim 3 is the cylinder liner according to claim 1 or 2, wherein the cylinder liner is formed on the outer peripheral surface of the cylinder liner, and the outer peripheral surface of the cylinder liner corresponding to the space between the cylinder bores of the cylinder block. The gist is that the film is not formed.

  According to the above invention, since the thermal conductivity between the cylinder block and the cylinder liner is reduced in a range other than between the cylinder bores in the circumferential direction of the cylinder, the difference between the temperature of the portion other than the cylinder bore and the temperature between the cylinder bores is reduced. Will be able to. It should be noted that between cylinder bores, heat from adjacent cylinders tends to be trapped, and therefore the temperature of the cylinder tends to be higher than in locations other than between the cylinder bores in the circumferential direction of the cylinder.

The block diagram which shows the whole structure of the engine provided with the cylinder liner about 1st Embodiment which actualized the cylinder liner concerning this invention. The perspective view which shows the perspective structure about the cylinder liner of the embodiment. The figure which shows an example of the composition ratio of the cast iron used as the raw material about the cylinder liner of the embodiment. The model figure which shows the processus | protrusion of the constricted shape about the cylinder liner of the embodiment. The model figure which shows the processus | protrusion of the constricted shape about the cylinder liner of the embodiment. [A] Sectional drawing which shows the cross-section along an axial direction about the cylinder liner of the embodiment. [B] The graph which shows an example of the relationship between the position of an axial direction, and cylinder wall temperature about the cylinder liner of the embodiment. [A] Sectional drawing which shows the cross-section along an axial direction about the cylinder liner of the embodiment. [B] The graph which shows an example of the relationship between the position of an axial direction, and film thickness about the cylinder liner of the embodiment. Sectional drawing which shows the enlarged structure of the ZC part of FIG. 6 about the cylinder liner of the embodiment. Sectional drawing which shows the cross-section of the ZA part of FIG. 1 about the cylinder liner of the embodiment. Sectional drawing which shows the cross-section of the ZB part of FIG. 1 about the cylinder liner of the embodiment. The process figure which shows the list of a manufacturing process about manufacture of the cylinder liner by metal mold | die centrifugal casting. The figure which shows the formation aspect of the constricted-shaped concave hole in a coating layer about manufacture of the cylinder liner by metal mold | die centrifugal casting. The figure which shows an example of the measurement procedure of each parameter by the three-dimensional laser measuring method about the cylinder liner of the embodiment. The figure which shows an example of the contour map obtained by the three-dimensional laser measuring method about the cylinder liner of the embodiment. The figure which shows the relationship between measurement height and a contour line about the cylinder liner of the embodiment. The figure which shows an example of the contour map obtained by the three-dimensional laser measuring method about the cylinder liner of the embodiment. The figure which shows an example of the contour map obtained by the three-dimensional laser measuring method about the cylinder liner of the embodiment. The figure which shows an example of the evaluation procedure of liner joining strength by a tension test about the cylinder block provided with the cylinder liner of the embodiment. Sectional drawing which shows the enlarged structure of the ZC part of FIG. 6 about 2nd Embodiment which actualized the cylinder liner concerning this invention. Sectional drawing which shows the cross-section of the ZA part of FIG. 1 about the cylinder liner of the embodiment. The figure which shows an example of the formation procedure of the film | membrane by arc spraying about the cylinder liner of the embodiment. Sectional drawing which shows the enlarged structure of the ZC part of FIG. 6 about 3rd Embodiment which actualized the cylinder liner concerning this invention. Sectional drawing which shows the cross-section of the ZA part of FIG. 1 about the cylinder liner of the embodiment. Sectional drawing which shows the enlarged structure of the ZC part of FIG. 6 about 4th Embodiment which actualized the cylinder liner concerning this invention. Sectional drawing which shows the cross-section of the ZA part of FIG. 1 about the cylinder liner of the embodiment. Sectional drawing which shows the enlarged structure of the ZC part of FIG. 6 about 5th, 6th, 7th, 8th, 9th, and 10th embodiment which actualized the cylinder liner concerning this invention. Sectional drawing which shows the cross-section of the ZA part of FIG. 1 about the cylinder liner of the embodiment.

An embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, it is assumed that the present invention is embodied as an engine cylinder liner made of an aluminum alloy.

<Engine configuration>
FIG. 1 shows an overall configuration of an engine provided with a cylinder liner according to the present invention.
The engine 1 includes a cylinder block 11, a cylinder head 12, and the like.

The cylinder block 11 includes a plurality of cylinders 13.
The cylinder 13 includes the cylinder liner 2.
In the cylinder block 11, a wall surface (cylinder inner wall 14) on the inner peripheral side of the cylinder 13 is formed by the inner peripheral surface (liner inner peripheral surface 21) of the cylinder liner 2. A cylinder bore 15 is formed surrounded by the liner inner circumferential surface 21.

The cylinder liner 2 is joined to the cylinder block 11 on the outer peripheral surface (liner outer peripheral surface 22) side through a cast ball made of a casting material.
In addition, as an aluminum alloy used as the material of the cylinder block 11, for example, “JIS”
ADC10 (related standard: US ASTM A380.0) "or" JIS ADC12 (related standard: US ASTM A383.0) "can be used. In the present embodiment, the ADC 12 is employed as an aluminum alloy that is a material of the cylinder block.

<Configuration of cylinder liner>
FIG. 2 shows a perspective structure of a cylinder liner to which the present invention is applied.
The cylinder liner 2 is formed from cast iron.

  The composition of cast iron can be set as shown in FIG. 3, for example. Basically, the “basic composition” is selected as the cast iron composition, but the components shown in the “auxiliary composition” can be added as necessary.

In the cylinder liner 2, a plurality of constricted projections (projections 3) are formed on the liner outer peripheral surface 22.
The protrusion 3 is formed on the entire liner outer peripheral surface 22 from the upper end of the cylinder liner 2 (liner upper end 23) to the lower end of the cylinder liner 2 (liner lower end 24). The liner upper end 23 indicates the end of the cylinder liner 2 located on the combustion chamber side in the engine 1. The liner lower end 24 indicates an end portion of the cylinder liner 2 located on the opposite side of the engine 1 from the combustion chamber.

In the cylinder liner 2, a film 5 is formed on the liner outer peripheral surface 22 and the surface of the protrusion 3.
On the liner outer peripheral surface 22, the coating 5 is formed in a range from the axial intermediate portion (liner intermediate portion 25) to the liner lower end 24. Moreover, the film 5 is formed over the entire circumferential direction.

  The coating 5 is constituted by a ceramic material sprayed layer (ceramic sprayed layer 51). In the present embodiment, alumina is employed as the ceramic material that is the material of the ceramic sprayed layer 51. Note that the thermal spray layer indicates a coating formed by thermal spraying (plasma spraying, HVOF thermal spraying, or the like).

<Structure of protrusion>
FIG. 4 shows a model diagram of the protrusion 3. Hereinafter, the radial direction (arrow A direction) of the cylinder liner 2 is defined as the axial direction of the protrusion 3. The axial direction of the cylinder liner 2 (arrow B direction) is the radial direction of the protrusion 3. FIG. 4 shows the shape of the protrusion 3 as seen from the radial direction of the protrusion 3.

The protrusion 3 is formed integrally with the cylinder liner 2. Further, the base end portion 31 is connected to the liner outer peripheral surface 22.
A top surface 32 </ b> A corresponding to the front end surface of the protrusion 3 is formed smoothly at the front end portion 32 of the protrusion 3.

A constricted portion 33 is formed between the proximal end portion 31 and the distal end portion 32 in the axial direction of the protrusion 3.
The constricted portion 33 is formed so that the cross-sectional area along the radial direction (radial cross-sectional area SR) is smaller than the radial cross-sectional area SR of the base end portion 31 and the distal end portion 32.

The protrusion 3 is formed so that the radial sectional area SR gradually increases from the constricted portion 33 to the proximal end portion 31 and the distal end portion 32.
FIG. 5 shows a model diagram of the protrusion 3 marked on the constricted space 34 of the cylinder liner 2.

In the cylinder liner 2, a constricted space 34 (shaded area) is formed through the constricted portion 33 of the protrusion 3.
The constricted space 34 is formed by a curved surface (the straight line DD corresponds to the curved surface in FIG. 5) passing through the maximum tip 32B along the axial direction of the protrusion 3 and the surface of the constricted portion 33 (constricted surface 33A). Corresponds to the enclosed area. The maximum tip portion 32B indicates a portion where the length in the radial direction of the protrusion 3 is the largest at the tip portion 32.

  In the engine 1 including the cylinder liner 2, the cylinder block 11 and the cylinder liner 2 are joined in a state where the material of the cylinder block 11 enters the constricted space 34 (the cylinder block 11 and the protrusion 3 are engaged with each other). Therefore, the bonding strength (liner bonding strength) between the cylinder block 11 and the cylinder liner 2 is sufficiently ensured. Further, since the deformation of the cylinder bore 15 is suppressed by improving the liner bonding strength, the fuel consumption rate can be improved through the reduction of friction.

<Formation of film>
With reference to FIG. 6, FIG. 7 and FIG. 8, the formation mode of the film 5 in the cylinder liner 2 will be described. Hereinafter, the thickness of the film 5 is indicated as a film thickness TP.

[1] “Film formation position”
With reference to FIG. 6, the setting aspect of the formation position of the film | membrane 5 is demonstrated. FIG. 6A shows a cross-sectional structure of the cylinder liner 2 along the axial direction. FIG. 6B shows an example of a change tendency in the axial direction of the cylinder temperature (cylinder wall temperature TW) in the steady operation state of the engine. Hereinafter, the cylinder liner in which the film 5 is removed from the cylinder liner 2 will be referred to as a reference cylinder liner. An engine having a reference cylinder liner is used as a reference engine.

In this embodiment, the formation position of the film 5 in the cylinder liner 2 is set based on the cylinder wall temperature TW of the reference engine.
Here, the changing tendency of the cylinder wall temperature TW in the reference engine will be described. In FIG. 6B, the solid line indicates the cylinder wall temperature TW of the reference engine, and the broken line indicates the cylinder wall temperature TW of the engine 1 of the present embodiment. Hereinafter, the maximum temperature in the cylinder wall temperature TW is referred to as the maximum cylinder wall temperature TWH, and the minimum temperature in the cylinder wall temperature TW is referred to as the minimum cylinder wall temperature TWL.

In the reference engine, the cylinder wall temperature TW changes as follows.
(A) In the range from the liner lower end 24 to the liner intermediate portion 25, the influence of the combustion gas is small, so that the cylinder wall temperature TW gradually increases from the liner lower end 24 to the liner intermediate portion 25. In the vicinity of the liner lower end 24, the cylinder wall temperature TW becomes the minimum cylinder wall temperature TWL1. In the present embodiment, a portion where the cylinder wall temperature TW shows such a change tendency in the cylinder liner 2 is defined as the liner low temperature portion 27.
(B) In the range from the liner intermediate portion 25 to the liner upper end 23, the influence of the combustion gas is large, so that the cylinder wall temperature TW rapidly increases. Further, in the vicinity of the liner upper end 23, the cylinder wall temperature TW becomes the maximum cylinder wall temperature TWH. In the present embodiment, the portion where the cylinder wall temperature TW shows such a change tendency in the cylinder liner 2 is the liner high temperature portion 26.

  In a normal engine such as the above-mentioned reference engine, the cylinder wall temperature TW is significantly lower than the appropriate temperature at a location corresponding to the liner low temperature portion 27, so that the viscosity of the engine oil in the vicinity thereof is excessively increased. Accordingly, the fuel consumption rate is inevitably deteriorated with the increase in piston friction. Note that the deterioration of the fuel consumption rate due to the low cylinder wall temperature TW appears more prominently in an engine having a relatively high thermal conductivity of the cylinder block (for example, an engine made of an aluminum alloy).

  Therefore, in the cylinder liner 2 according to the present embodiment, the thermal conductivity between the cylinder block 11 and the liner low temperature portion 27 is reduced by forming the coating 5 on the liner low temperature portion 27, so that the cylinder wall of the liner low temperature portion 27 is reduced. The temperature TW is reduced.

  In the engine 1 of the present embodiment, the cylinder block 11 and the liner low-temperature portion 27 are joined via the coating 5 having a heat insulating action, so that the thermal conductivity between the cylinder block 11 and the liner low-temperature portion 27 is high. It begins to decline. As a result, the cylinder wall temperature TW of the liner low-temperature portion 27 increases, so that the minimum cylinder wall temperature TWL becomes a minimum cylinder wall temperature TWL2 that is higher than the minimum cylinder wall temperature TWL1. Then, as the viscosity of the engine oil decreases as the cylinder wall temperature TW increases, the friction of the piston is reduced, so that the fuel consumption rate can be improved.

  The boundary (wall temperature boundary 28) between the liner high temperature portion 26 and the liner low temperature portion 27 can be grasped based on the cylinder wall temperature TW of the reference engine. On the other hand, the length of the liner low temperature portion 27 (the length from the cylinder lower end 24 to the wall temperature boundary 28) is often the length of the cylinder liner 2 (the length from the liner upper end 23 to the liner lower end 24 (liner). It has been confirmed that the total length is about 2/3 to 3/4. Therefore, when setting the formation position of the film 5, the range from the liner lower end 24 to 2/3 to 3/4 of the entire length of the liner can be handled as the liner low temperature portion 27 without strictly grasping the wall temperature boundary 28. .

[2] “Thickness of coating”
With reference to FIG. 7, the setting aspect of film thickness TP is demonstrated. FIG. 7A shows a cross-sectional structure of the cylinder liner 2 along the axial direction. FIG. 7B shows the relationship between the axial position of the cylinder liner 2 and the film thickness TP.

In the cylinder liner 2, the film thickness TP is set as follows.
(A) The film thickness TP is gradually increased from the wall temperature boundary 28 to the liner lower end 24. That is, while the wall temperature boundary 28 is set to “0”, the liner lower end 24 is set to the largest thickness (maximum thickness TPmax).
(B) The film thickness TP is set to 0.5 mm or less. In the present embodiment, the coating 5 is formed so that the average value of the coating thickness TP at a plurality of locations of the liner low-temperature portion 27 is 0.5 mm or less. The film 5 can also be formed so that TP is 0.5 mm or less.

[3] “Form of coating around projections”
FIG. 8 shows an enlarged structure of the ZC portion of FIG.
In the cylinder liner 2, a coating 5 is formed along the liner outer peripheral surface 22 and the surface of the protrusion 3. Further, the film 5 is formed so that the constricted space 34 is not filled. That is, the coating 5 is formed so that the casting material flows into the constricted space 34 when the cylinder liner 2 is cast. When the constricted space 34 is filled with the film 5, the cast material is not filled in the constricted space 34, and thus the anchor effect by the protrusion 3 cannot be obtained in the liner low temperature portion 27.

<Joint state between cylinder block and cylinder liner>
With reference to FIG.9 and FIG.10, the joining state of the cylinder block 11 and the cylinder liner 2 is demonstrated. 9 and 10 each show a cross-sectional structure of the cylinder block 11 along the axial direction of the cylinder 13.

[1] "Joint state of liner low temperature part"
FIG. 9 shows a joined state of the cylinder block 11 and the liner low-temperature part 27 (cross-sectional structure of the ZA part in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  As for the joining state between the cylinder block 11 and the film 5, the film 5 is formed through alumina having a thermal conductivity smaller than that of the cylinder block 11, so that the cylinder block 11 and the film 5 have a low thermal conductivity. Are joined together.

In the engine 1, the cylinder block 11 and the liner low-temperature part 27 are joined in such a state, so that the following effects can be obtained.
(A) Since the thermal conductivity between the cylinder block 11 and the liner low temperature portion 27 is lowered through the coating 5, the cylinder wall temperature TW of the liner low temperature portion 27 can be increased.

  (B) Since the bonding strength between the cylinder block 11 and the liner low temperature portion 27 is ensured through the protrusion 3, separation between the cylinder block 11 and the liner low temperature portion 27 is suppressed.

[2] “Joint state of liner high temperature part”
FIG. 10 shows a joined state of the cylinder block 11 and the liner high temperature portion 26 (cross-sectional structure of the ZB portion in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner high temperature portion 26 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. As a result, the bonding strength between the cylinder block 11 and the liner high temperature portion 26 is sufficiently ensured through the anchor effect of the protrusion 3. In addition, sufficient thermal conductivity is ensured between the cylinder block 11 and the liner high temperature portion 26.

<Formation of protrusions>
With reference to Table 1, the formation state of the protrusion 3 in the cylinder liner 2 will be described.
In the present embodiment, “first area ratio SA”, “second area ratio SB”, “standard cross-sectional area SD”, “standard number of protrusions NP” are set as parameters indicating the formation state of the protrusions 3 (formation state parameters). “Standard protrusion length HP” is defined.

Here, the “measurement height H”, “first reference plane PA”, and “second reference plane PB”, which are the basis of the formation state parameters, will be described.
(A) “Measured height H” indicates the distance in the axial direction of the protrusion 3 (height of the protrusion 3) with respect to the liner outer peripheral surface 22. The measurement height H at the liner outer peripheral surface 22 is 0 mm. Further, the measurement height H is the largest on the top surface 32A of the protrusion 3.
(B) The “first reference plane PA” indicates a plane along the radial direction of the protrusion 3 at a position where the measurement height is 0.4 mm.
(C) The “second reference plane PB” indicates a plane along the radial direction of the protrusion 3 at a measurement height of 0.2 mm.

The contents of the formation state parameter will be described.
[A] “First Area Ratio SA”: The first area ratio SA indicates the ratio of the area of the protrusion 3 (radial sectional area SR) to the unit area of the first reference plane PA on the liner outer peripheral surface 22.
[B] “Second Area Ratio SB”: The second area ratio SB indicates the ratio of the area of the protrusion 3 (radial cross-sectional area SR) to the unit area of the second reference plane PB on the liner outer peripheral surface 22.
[C] “Standard Cross-sectional Area SD”: The standard cross-sectional area SD indicates the area (radial cross-sectional area SR) of one protrusion 3 on the first reference plane PA on the liner outer peripheral surface 22.
[D] “Standard number of protrusions NP”: The standard number of protrusions NP indicates the number of protrusions 3 formed per unit area (1 cm ² ) on the liner outer peripheral surface 22.
[E] “Standard protrusion length HP”: The standard protrusion length HP indicates an average value of the measurement heights H at a plurality of positions on the protrusion 3.

本実施形態では、上記〔Ａ〕〜〔Ｅ〕の形成状態パラメータを表１の選択範囲内の値に設定することで、突起３によるライナ接合強度の向上の効果をさらに高めるとともに、突起３間における鋳造材料の充填性の向上を図るようにしている。また、上記パラメータの設定の他に、第１基準平面ＰＡ上において各突起３が独立して存在するようにシリンダライナ２を形成することで、より高い充填性が得られるようにもしている。

In the present embodiment, by setting the formation state parameters [A] to [E] to values within the selection range of Table 1, the effect of improving the liner bonding strength by the protrusions 3 is further enhanced, and the distance between the protrusions 3 is increased. The filling property of the casting material is improved. In addition to the above parameter setting, the cylinder liner 2 is formed so that the protrusions 3 exist independently on the first reference plane PA, so that a higher filling property can be obtained.

<Cylinder liner manufacturing method>
A method for manufacturing the cylinder liner 2 will be described with reference to FIGS.
In the present embodiment, the cylinder liner 2 is manufactured by mold centrifugal casting. Further, in order to keep the value of the formation state parameter within the selection range of Table 1, the values of parameters (hereinafter referred to as [A] to [F]) related to the mold centrifugal casting are set within the selection range of Table 2. I am doing so.
[A] Mixing ratio of the refractory base material 61A in the suspension 61.
[B] Mixing ratio of the binder 61B in the suspension 61.
[C] The mixing ratio of water 61C in the suspension 61.
[D] Average particle diameter of the refractory base material 61A.
[E] Ratio of addition of surfactant 62 to suspension 61.
[F] Thickness of layer of coating agent 63 (coating layer 64).

シリンダライナ２の製造は、図１１に示す手順をもって行われる。

The cylinder liner 2 is manufactured according to the procedure shown in FIG.

  [Step A] A suspension 61 is prepared by blending refractory base material 61A, binder 61B, and water 61C in a predetermined ratio. In this step, the blending ratio of the refractory base material 61A, the binder 61B and the water 61C, and the average particle diameter of the refractory base material 61A are set to values within the selection range of Table 2.

  [Step B] A predetermined amount of a surfactant 62 is added to the suspension 61 to form a coating agent 63. In this step, the addition ratio of the surfactant 62 to the suspension 61 is set to a value within the selection range shown in Table 2.

  [Step C] After the rotating mold 65 is heated to a specified temperature, the coating agent 63 is sprayed onto the inner peripheral surface (mold inner peripheral surface 65A). At this time, the coating agent 63 is applied so that the layer of the coating agent 63 (the coating layer 64) is formed with a substantially uniform thickness over the entire circumference of the inner peripheral surface 65A of the mold. In this step, the thickness of the coating layer 64 is set to a value within the selection range of Table 2.

In the coating layer 64 of the mold 65, a concave hole having a constricted shape is formed after the above [Step C] is performed.
With reference to FIG. 12, the formation aspect of the constricted concave hole is demonstrated.
[1] On the inner peripheral surface 65A of the mold 65, the coating layer 64 is formed in a state including a plurality of bubbles 64A.
[2] When the surfactant 62 acts on the bubbles 64 </ b> A, a concave hole 64 </ b> B is formed on the inner peripheral side of the coating layer 64.
[3] By enlarging the tip of the recessed hole 64B until it abuts against the inner peripheral surface 65A of the mold, a recessed hole 64C having a shape confined in the coating layer 64 is formed.

  [Step D] After the coating layer 64 is dried, a cast iron melt 66 is cast into the rotating mold 65. At this time, since the molten metal 66 flows into the concavity-shaped concave hole 64 </ b> C of the coating layer 64, a constriction (protrusion 3) constricted to the cylinder liner 2 after casting is formed.

[Step E] After the molten metal 66 is solidified to form the cylinder liner 2, the cylinder liner 2 is removed from the mold 65 together with the coating layer 64.
[Step F] The coating layer 64 (coating agent 63) is removed from the outer periphery of the cylinder liner 2 by the blast processing device 67.

<Measuring method of formation state parameter>
With reference to FIG. 13, a method for measuring formation state parameters by a three-dimensional laser measurement method will be described. The standard protrusion length HP is measured by a separate method.

Each formation state parameter can be measured by the following procedure.
[1] A test piece 71 for measuring protrusions is created from the cylinder liner 2.
[2] In the non-contact type three-dimensional laser measuring device 81, the projection measuring test piece 71 is set on the test table 83 so that the irradiation direction of the laser beam 82 and the axial direction of the projection 3 are substantially parallel (see FIG. 13 [A]).
[3] A laser beam 82 is irradiated from the three-dimensional laser measuring instrument 81 toward the test piece 71 for measuring protrusions. (FIG. 13 [B]).
[4] The measurement result of the three-dimensional laser measuring device 81 is taken into the image processing device 84.
[5] A contour map 85 (FIG. 14) of the protrusion 3 is displayed through image processing by the image processing device 84, and each formation state parameter is calculated based on the contour map 85.

<Contour map of protrusion>
With reference to FIGS. 14 and 15, a contour diagram 85 of the protrusion 3 will be described. FIG. 14 shows an example of a contour map 85. FIG. 15 shows the relationship between the measured height H and the contour line HL. FIG. 14 shows a contour diagram 85 for a protrusion 3 different from the protrusion 3 of FIG.

In the contour map 85, a contour line HL is displayed for every fixed measurement height H.
For example, when the contour line HL is displayed every 0.2 mm in the range from the measurement height of 0 mm to the measurement height of 1.0 mm, in the contour diagram 85, the contour line HL0 of the measurement height of 0 mm, the measurement height of 0. A 2 mm contour line HL2, a measurement height 0.4 mm contour line HL4, a measurement height 0.6 mm contour line HL6, a measurement height 0.8 mm contour line HL8, and a measurement height 1.0 mm contour line HL10 are displayed.

  In FIG. 15, the contour line HL4 corresponds to the first reference plane PA. Further, the contour line HL2 corresponds to the second reference plane PB. Although the case where the contour lines HL are displayed at intervals of 0.2 mm is illustrated here, the contour lines HL can be displayed at appropriate intervals in the actual contour map 85.

  The first region RA and the second region RB in the contour map 85 will be described with reference to FIGS. FIG. 16 shows a contour map 85 (first contour map 85A) in which the contour lines HL other than the contour line HL4 having a measurement height of 0.4 mm are not displayed. FIG. 17 shows a contour map 85 (second contour map 85B) in which the contour lines HL other than the contour line HL2 having a measurement height of 0.2 mm are not displayed. 16 and 17, the solid lines indicate the contour lines HL in the display state, and the broken lines indicate the contour lines HL in the non-display state.

  In the present embodiment, the region surrounded by the contour line HL4 in the contour map 85 is the first region RA. That is, the hatched area in the first contour map 85A corresponds to the first area RA. In the contour map 85, a region surrounded by the contour line HL2 is a second region RB. That is, the hatched area in the second contour map 85B corresponds to the second area RB.

<Calculation method of formation state parameter>
Regarding the cylinder liner 2 of the present embodiment, the formation state parameter can be calculated as follows based on the contour map 85.

[A] "About the first area ratio SA"
The first area ratio SA can be calculated as a ratio of the area of the first region RA to the area of the contour map 85. That is, the first area ratio SA can be calculated by the following formula.

SA = SRA / ST x 100 [%]

In the above formula, “ST” indicates the entire area of the contour map 85. “SRA” represents the total area of the first regions RA in the contour map 85. For example, when the first contour map 85A of FIG. 16 is used as a model, the area of the square region is “ST”. Further, the area of the hatched area is “SRA”. In calculating the first area ratio SA, it is assumed that the contour map 85 does not include a portion other than the liner outer peripheral surface 22.

[B] “About the second area ratio SB”
The second area ratio SB can be calculated as a ratio of the area of the second region RB to the area of the contour map 85. That is, the second area ratio SB can be calculated by the following formula.

SB = SRB / ST x 100 [%]

In the above formula, “ST” indicates the entire area of the contour map 85. “SRB” represents the total area of the second regions RB in the contour map 85. For example, when the second contour diagram 85B of FIG. 17 is used as a model, the area of the square region is “ST”. The area of the hatched area is “SRB”. In calculating the second area ratio SB, it is assumed that the contour map 85 does not include a portion other than the liner outer peripheral surface 22.

[C] “Standard cross-sectional area SD”
The standard cross-sectional area SD can be calculated as the area of each first region RA in the contour map 85. For example, when the first contour diagram 85A in FIG. 16 is used as a model, the area of the hatched area is the standard cross-sectional area SD.

[D] “Standard number of protrusions NP”
The standard protrusion number NP can be calculated as the number of protrusions 3 per unit area (here, 1 cm ² ) in the contour diagram 85. For example, when the first contour diagram 85A in FIG. 16 or the second contour diagram 85B in FIG. 17 is used as a model, the number of projections (one) in the figure is the standard projection number NP. In the cylinder liner 2 of the present embodiment, since 5 to 60 protrusions 3 are formed per unit area (1 cm ² ), the actual standard protrusion number NP and the first contour diagrams 85A and 2 The value is different from the standard projection number NP in the contour diagram 85B.

[E] “Standard protrusion length HP”
The standard protrusion length HP can be calculated as an average value of the height of one or a plurality of positions measured for each protrusion 3. In addition, the height of the protrusion 3 can be measured by a measuring device such as a dial depth gauge.

  Whether or not each projection 3 exists independently on the first reference plane PA can be confirmed based on the first region RA in the contour map 85. That is, it can be confirmed that the protrusions 3 are independent on the first reference plane PA because the first regions RA do not interfere with each other.

<Method for evaluating bonding strength>
An example of an evaluation mode of the bonding strength between the cylinder block 11 and the cylinder liner 2 will be described.

FIG. 18 shows an example of a method for evaluating the bonding strength.
The evaluation of the bonding strength can be performed by the following procedures [1] to [5].
[1] An aluminum alloy single cylinder cylinder block 72 provided with the cylinder liner 2 is manufactured by die casting (FIG. 18 [A]).
[2] A test piece 74 for strength evaluation is created from the cylinder 73 of the single cylinder cylinder block 72. The strength evaluation test piece 74 is composed of a part of the liner low temperature portion 27 (liner piece 74A and coating 5) of the cylinder liner 2 and an aluminum portion (aluminum piece 74B) of the cylinder 73. [3] The arm 86 of the tensile tester is bonded to the strength evaluation test piece 74 (the liner piece 74A and the aluminum piece 74B) (FIG. 18B).
[4] After holding one of the arms 86 of the tensile tester by the clamp 87, the strength is obtained through the other arm 86 so that the liner piece 74A and the aluminum piece 74B are separated in the radial direction of the cylinder (direction of arrow C). A tensile load is applied to the test specimen 74 for evaluation (FIG. 18 [C]).
[5] The strength (load per unit area) when the liner piece 74A and the aluminum piece 74B are peeled through the tensile test is calculated as the liner bonding strength. In addition, also about the liner high temperature part 26 of the cylinder liner 2, evaluation of joining strength can be performed with the procedure of said [1]-[5].

  Regarding the engine 1 of this embodiment, when the joint strength between the cylinder block 11 and the cylinder liner 2 was measured by the above evaluation method, it was confirmed that the joint strength was sufficiently higher than that of the reference engine.

<Effect of embodiment>
As described above in detail, according to the cylinder liner of the present embodiment, the following effects can be obtained.

  (1) In the cylinder liner 2 of the present embodiment, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27. As a result, the cylinder wall temperature TW of the liner low-temperature portion 27 in the engine 1 increases, so that the fuel consumption rate can be improved through a decrease in the viscosity of the engine oil.

  (2) In the cylinder liner 2 of the present embodiment, a plurality of protrusions 3 are formed on the liner outer peripheral surface 22. Thereby, since the cylinder block 11 and the cylinder liner 2 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other, the joining strength between the cylinder block 11 and the cylinder liner 2 can be sufficiently ensured. Become. Further, the deformation of the cylinder bore 15 can be suppressed through the improvement of the bonding strength.

  (3) In the cylinder liner 2 of the present embodiment, the coating 5 is formed so that the coating thickness TP is 0.5 mm or less. Thereby, the fall of the joint strength of the cylinder block 11 and the liner low temperature part 27 can be suppressed now. In addition, when the film thickness TP is larger than 0.5 mm, the anchor effect by the protrusion 3 is reduced, so that the bonding strength between the cylinder block 11 and the liner low-temperature portion 27 is significantly reduced.

  (4) In the cylinder liner 2 of the present embodiment, the protrusions 3 are formed so that the standard protrusion number NP is included in the range of “5 to 60”. As a result, the liner bonding strength can be improved. Moreover, the filling property of the casting material between the protrusions 3 can be improved.

  When the standard projection number NP is out of the selection range, the following problems occur. When the number of standard protrusions NP is less than 5, the number of protrusions 3 is insufficient, leading to a decrease in liner bonding strength. When the number of standard protrusions NP is larger than 60, the space between the protrusions 3 is narrow, and the filling property of the casting material between the protrusions 3 is lowered.

  (5) In the cylinder liner 2 of the present embodiment, the protrusion 3 is formed so that the standard protrusion length HP is included in the range of “0.5 mm to 1.0 mm”. As a result, the liner bonding strength and the outer diameter accuracy of the cylinder liner 2 can be improved.

  When the standard protrusion length HP is out of the selection range, the following problems occur. When the standard protrusion length HP is smaller than 0.5 mm, the height of the protrusion 3 is insufficient, resulting in a decrease in liner bonding strength. When the standard protrusion length HP is larger than 1.0 mm, the protrusion 3 is likely to be broken, leading to a decrease in liner bonding strength. Moreover, since the height of the protrusion 3 is not uniform, the outer diameter accuracy is lowered.

  (6) In the cylinder liner 2 of the present embodiment, the protrusions 3 are formed so that the first area ratio SA is included in the range of “10% to 50%”. As a result, a sufficiently large liner bonding strength can be ensured. Moreover, the filling property of the casting material between the protrusions 3 can be improved.

  When the first area ratio SA is out of the selection range, the following problem occurs. When the first area ratio SA is smaller than 10%, the liner bonding strength is significantly reduced as compared with the case where the first area ratio SA is 10% or more. When the first area ratio SA is larger than 50%, the second area ratio SB exceeds the upper limit value (55%), so that the filling property of the casting material between the protrusions 3 is significantly lowered.

  (7) In the cylinder liner 2 of the present embodiment, the protrusion 3 is formed so that the second area ratio SB is included in the range of “20% to 55%”. Thereby, the filling property of the casting material between the protrusions 3 can be improved. In addition, a sufficiently large liner bonding strength can be ensured.

  When the second area ratio SB is out of the selection range, the following problem occurs. When the second area ratio SB is smaller than 20%, the first area ratio SA is less than the lower limit (10%), which leads to a significant decrease in liner bonding strength. When the second area ratio SB is larger than 55%, the filling property of the casting material between the protrusions 3 is significantly lowered as compared with the case where the second area ratio SB is 55% or less.

(8) In the cylinder liner 2 of the present embodiment, the protrusion 3 is formed so that the standard cross-sectional area SD is included in the range of “0.2 mm ^{2 to} 3.0 mm ² ”. Thereby, breakage of the protrusion 3 in the manufacturing process of the cylinder liner 2 can be suppressed. Moreover, the filling property of the casting material between the protrusions 3 can be improved.

In addition, when the standard cross-sectional area SD is out of the selection range, the following problem occurs. When the standard cross-sectional area SD is smaller than 0.2 mm ² , the strength of the projection 3 is insufficient, and thus the projection 3 is damaged in the manufacturing process of the cylinder liner 2. When the standard cross-sectional area SD is larger than 3.0 mm ² , the filling property of the casting material between the protrusions 3 decreases due to the narrow interval between the protrusions 3.

  (9) In the cylinder liner 2 of the present embodiment, the protrusions 3 are formed so that each protrusion 3 (first region RA) exists independently on the first reference plane PA. Thereby, the filling property of the casting material between the protrusions 3 can be improved. In addition, when each protrusion 3 (1st area | region RA) is not independent on 1st reference plane PA, since the space | interval of protrusion 3 is narrow, the filling property of the casting material between protrusions 3 falls. Become.

  (10) In the engine, the cylinder bore thermally expands due to an increase in the cylinder wall temperature TW. On the other hand, since the cylinder wall temperature TW differs in the axial direction, the amount of deformation of the cylinder bore also becomes different in the axial direction. Such a difference in the deformation amount of the cylinder bore leads to an increase in piston friction, and is one of the factors that deteriorate the fuel consumption rate.

  Therefore, in the cylinder liner 2 of the present embodiment, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27, while the coating 5 is not formed on the liner outer peripheral surface 22 of the liner high temperature portion 26.

  As a result, the cylinder wall temperature TW (the broken line in FIG. 6B) of the liner low temperature portion 27 of the engine 1 rises higher than the cylinder wall temperature TW of the liner low temperature portion 27 of the reference engine (solid line in FIG. 6B). On the other hand, the cylinder wall temperature TW (the broken line in FIG. 6B) of the liner high temperature portion 26 of the engine 1 is approximately the same as the cylinder wall temperature TW (the solid line in FIG. 6B) of the liner high temperature portion 26 of the reference engine. It becomes.

  Accordingly, in the engine 1, the difference between the minimum cylinder wall temperature TWL and the maximum cylinder wall temperature TWH (cylinder wall temperature difference ΔTW) is smaller than the cylinder wall temperature difference ΔTW of the reference engine, so that the cylinder bore 15 is deformed in the axial direction. The difference in amount is reduced (the amount of deformation is made uniform). And since the friction of the piston is reduced by making the deformation amount uniform, the fuel consumption rate can be improved.

  (11) In the cylinder liner 2 of the present embodiment, the coating thickness TP is gradually set from the wall temperature boundary 28 to the liner lower end 24. Accordingly, since the thermal conductivity between the cylinder block 11 and the cylinder liner 2 decreases toward the liner lower end 24, the difference in the cylinder wall temperature TW in the axial direction of the liner low temperature portion 27 can be reduced. Become.

<Other configuration of the embodiment>
In addition, the said 1st Embodiment can also be implemented as the following forms which changed this suitably, for example.

  In the first embodiment, the coating 5 is formed so that the coating thickness TP gradually increases from the wall temperature boundary 28 to the liner lower end 24, but the coating thickness TP is substantially uniform in the liner low-temperature portion 27. It can also be set. In short, the setting mode of the film thickness TP can be appropriately changed within a range in which the cylinder wall temperature TW does not greatly deviate from the appropriate temperature in the entire liner low temperature portion 27.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the film formation mode in the cylinder liner of the first embodiment is changed as described below. The cylinder liner of this embodiment is the same as that of the first embodiment except for the configuration described below.

<Formation of film>
FIG. 19 shows an enlarged structure of the ZC portion in FIG.
In the cylinder liner 2, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27.

The coating 5 is composed of a sprayed layer of iron-based material (iron sprayed layer 52).
The iron sprayed layer 52 is configured by stacking a plurality of small sprayed layers 52A. The iron sprayed layer 52 (small sprayed layer 52A) includes a large number of oxide layers and pores.

<Joint state between cylinder block and liner low temperature part>
FIG. 20 shows a joined state between the cylinder block 11 and the liner low-temperature portion 27 (cross-sectional structure of the ZA portion in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  With respect to the joining state between the cylinder block 11 and the coating 5, the coating 5 is formed through a thermal spray layer containing a large number of oxide layers and pores, so that the cylinder block 11 and the coating 5 are machined with low thermal conductivity. Are joined together.

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in such a state, which is described in “[1]“ Linear low temperature portion joined state ”” of the first embodiment (A ) And (B) can be obtained.

<Method for producing film>
With reference to FIG. 21, the manufacturing method of the membrane | film | coat 5 is demonstrated.
In this embodiment, the coating 5 is formed through arc spraying.

Formation of the film 5 can be performed by the following procedure.
[1] The wire 92 melted by the arc spraying device 91 is sprayed onto the liner outer peripheral surface 22 of the liner low-temperature portion 27 to form a small sprayed layer 52A (FIG. 21A).
[2] After forming one small sprayed layer 52A, another small sprayed layer 52A is formed on this small sprayed layer 52A (FIG. 21B).
[3] The operation of [2] is repeated until the film 5 having a predetermined thickness is formed.

  According to the above manufacturing method, the surface of the wire 92 that has been melted into particles is oxidized, so that an oxide layer is formed inside the iron sprayed layer 52 (small sprayed layer 52A). Thereby, the heat insulation performance of the membrane | film | coat 5 comes to be improved more.

  In the present embodiment, the diameter of the wire 92 used for arc spraying is set to 0.8 mm or more. As a result, the powder of the wire 92 having a relatively large particle size is sprayed to the liner low temperature portion 27, so that many pores are included in the formed iron sprayed layer 52. That is, the film 5 having higher heat insulation can be formed.

  When the diameter of the wire 92 is smaller than 0.8 mm, the powder of the wire 92 having a small particle diameter is sprayed to the liner low temperature portion 27, so that the diameter of the wire 92 is set to 0.8 mm or more. The number of pores contained in the iron sprayed layer 52 is greatly reduced.

<Effect of embodiment>
As described above in detail, according to the cylinder liner according to the second embodiment, the following effects can be obtained in addition to the effects (1) to (11) according to the first embodiment. It becomes like this.

  (12) In the cylinder liner 2 of the present embodiment, the iron sprayed layer 52 is composed of a plurality of small sprayed layers 52A. Thereby, since many oxide layers are formed inside the iron sprayed layer 52, the thermal conductivity between the cylinder block 11 and the liner low-temperature part 27 can be further reduced.

<Other configuration of the embodiment>
In addition, the said 2nd Embodiment can also be implemented as the following forms which changed this suitably, for example.

  In the second embodiment, the diameter of the wire 92 is set to 0.8 mm or more when the coating 5 is manufactured. However, the selection range of the diameter of the wire 92 can also be set as follows. That is, the selection range of the diameter of the wire 92 can be set to a range of “0.8 mm to 2.4 mm”. In addition, when the diameter of the wire 92 is made larger than 2.4 mm, it is considered that the strength of the iron sprayed layer 52 is greatly reduced due to excessively large particles of the wire 92.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS.
In this embodiment, in the cylinder liner of the first embodiment, the film formation mode is changed as described below. The cylinder liner of this embodiment is the same as that of the first embodiment except for the configuration described below.

<Formation of film>
FIG. 22 shows an enlarged structure of the ZC portion in FIG.
In the cylinder liner 2, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27. The coating 5 is composed of a first sprayed layer 53A formed on the surface of the cylinder liner 2 and a second sprayed layer 53B formed on the surface of the first sprayed layer 53A.

  The first sprayed layer 53A is composed of a sprayed layer of a ceramic material (alumina, zirconia, etc.). In addition, as a material of the first sprayed layer 53 </ b> A, a material that reduces the thermal conductivity between the cylinder block 11 and the liner low temperature portion 27 can be employed.

  The second sprayed layer 53B is composed of a sprayed layer of an aluminum alloy (such as an Al—Si alloy or an Al—Cu alloy). In addition, as a material of the 2nd sprayed layer 53B, a material with high joining property with the cylinder block 11 is employable.

<Joint state between cylinder block and liner low temperature part>
FIG. 23 shows a joined state between the cylinder block 11 and the liner low-temperature part 27 (cross-sectional structure of the ZA part in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  The joining state between the cylinder block 11 and the coating 5 is such that the cylinder block 11 and the coating 5 have low thermal conductivity because the coating 5 is formed including alumina having a lower thermal conductivity than the cylinder block 11. Are mechanically joined together.

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in such a state, which is described in “[1]“ Linear low temperature portion joined state ”” of the first embodiment (A ) And (B) can be obtained.

  Further, since the coating 5 is formed including the second sprayed layer 53B having a high bondability with the cylinder block 11, the cylinder block 11 and the coating are compared with the case where the coating 5 is formed only through the first sprayed layer 53A. The bonding strength with 5 is improved.

<Method for producing film>
In this embodiment, the film 5 is formed through plasma spraying.
Formation of the film 5 can be performed by the following procedure.
[1] A first sprayed layer 53A is formed on the liner low temperature portion 27 by a plasma spraying apparatus.
[2] After forming the first sprayed layer 53A, the second sprayed layer 53B is formed by a plasma spraying apparatus.

<Effect of embodiment>
As described above in detail, according to the cylinder liner according to the third embodiment, the following effects can be obtained in addition to the effects (1) to (11) according to the first embodiment. It becomes like this.

  (13) In the cylinder liner 2 of the present embodiment, the coating 5 is constituted by the first sprayed layer 53A and the second sprayed layer 53B. Accordingly, it is possible to improve the bondability between the cylinder block 11 and the coating 5 through the second sprayed layer 53B while ensuring the heat insulating effect of the coating 5 through the first sprayed layer 53A.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the film formation mode in the cylinder liner of the first embodiment is changed as described below. The cylinder liner of this embodiment is the same as that of the first embodiment except for the configuration described below.

<Formation of film>
FIG. 24 shows an enlarged structure of the ZC portion of FIG.
In the cylinder liner 2, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27. The film 5 is composed of an oxide layer (oxide layer 54).

<Joint state between cylinder block and liner low temperature part>
FIG. 25 shows a joined state of the cylinder block 11 and the liner low-temperature part 27 (cross-sectional structure of the ZA part in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  About the joining state of the cylinder block 11 and the membrane | film | coat 5, since the membrane | film | coat 5 is formed through the oxide, the cylinder block 11 and the membrane | film | coat 5 are mechanically joined in the state with low heat conductivity.

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in such a state, which is described in “[1]“ Linear low temperature portion joined state ”” of the first embodiment (A ) And (B) can be obtained.

<Method for producing film>
In this embodiment, the film 5 is formed through high frequency heating.
Formation of the film 5 can be performed by the following procedure.
[1] The liner low-temperature part 27 is heated by a high-frequency heating device.
[2] Heating is continued until an oxide layer 54 having a predetermined thickness is formed on the liner outer peripheral surface 22.

  According to the above manufacturing method, the tip portion 32 of the protrusion 3 is melted by heating the liner low temperature portion 27, so that the oxide layer 54 thicker than the other portions is formed at the tip portion 32. Therefore, the heat insulation performance around the tip 32 of the protrusion 3 can be improved. In addition, since the coating 5 having a sufficient thickness is formed also in the constricted portion 33 of the protrusion 3, the heat insulation performance around the constricted portion 33 can be further improved.

<Effect of embodiment>
As described above in detail, according to the cylinder liner according to the fourth embodiment, the following effects can be obtained in addition to the effects (1) to (11) according to the first embodiment. It becomes like this.

  (14) In the cylinder liner 2 of this embodiment, the coating 5 is formed by heating the cylinder liner 2. Thereby, the heat insulation performance around the constricted portion 33 can be improved. In addition, since it is not necessary to separately prepare a material for forming the film 5, it is possible to reduce labor and cost for managing the material.

(Fifth embodiment)
A fifth embodiment of the present invention will be described with reference to FIGS. 26 and 27. FIG.
In this embodiment, the film formation mode in the cylinder liner of the first embodiment is changed as described below. The cylinder liner of this embodiment is the same as that of the first embodiment except for the configuration described below.

<Formation of film>
FIG. 26 shows an enlarged structure of the ZC portion of FIG.
In the cylinder liner 2, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27. The film 5 is constituted by a layer of a release agent for die casting (release agent layer 55).

In forming the release agent layer 55, for example, the following release agent can be used.
-A mold release agent prepared by mixing vermiculite, mitazole and water glass at a predetermined ratio.
A release agent prepared by mixing a liquid material mainly composed of silicon and water glass at a predetermined ratio.

<Joint state between cylinder block and liner low temperature part>
FIG. 27 shows a joined state of the cylinder block 11 and the liner low-temperature part 27 (cross-sectional structure of the ZA part in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  About the joining state of the cylinder block 11 and the membrane | film | coat 5, when the membrane | film | coat 5 is formed through the mold release agent with low adhesiveness with the cylinder block 11, the cylinder block 11 and the membrane | film | coat 5 are joined via the space | gap 5H. ing. In manufacturing the cylinder block 11, the casting material is solidified in a state where there is a portion where the casting material and the release agent layer 55 are not sufficiently adhered to each other. A gap 5H is formed between them.

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in such a state, which is described in “[1]“ Linear low temperature portion joined state ”” of the first embodiment (A ) And (B) can be obtained.

<Effect of embodiment>
As described above in detail, according to the cylinder liner according to the fifth embodiment, the following effects can be obtained in addition to the effects (1) to (11) according to the first embodiment. It becomes like this.

  (15) In the cylinder liner 2 of the present embodiment, the coating 5 is formed using a mold release agent for die casting. As a result, when the coating 5 is formed, it is possible to divert the die-casting release agent or its material used when the cylinder block 11 is manufactured, so that it is possible to reduce man-hours and costs.

(Sixth embodiment)
A sixth embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the film formation mode in the cylinder liner of the first embodiment is changed as described below. The cylinder liner of this embodiment is the same as that of the first embodiment except for the configuration described below.

<Formation of film>
FIG. 26 shows an enlarged structure of the ZC portion of FIG.
In the cylinder liner 2, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27. The coating 5 is composed of a layer of a coating agent for mold centrifugal casting (a coating agent layer 56).

In forming the coating agent layer 56, for example, the following coating agent can be used.
・ Coating agent formulated with diatomaceous earth as the main component.
・ A coating agent formulated with graphite as the main component.

<Joint state between cylinder block and liner low temperature part>
FIG. 27 shows a joined state of the cylinder block 11 and the liner low-temperature part 27 (cross-sectional structure of the ZA part in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  About the joining state of the cylinder block 11 and the film 5, the cylinder block 11 and the film 5 are bonded via the gap 5H by forming the film 5 through a coating agent having low adhesion to the cylinder block 11. ing. When the cylinder block 11 is manufactured, the casting material is solidified in a state where there is a portion where the casting material and the coating agent layer 56 are not sufficiently adhered to each other. A gap 5H is formed between them.

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in such a state, which is described in “[1]“ Linear low temperature portion joined state ”” of the first embodiment (A ) And (B) can be obtained.

<Effect of embodiment>
As described above in detail, according to the cylinder liner according to the sixth embodiment, the following effects can be obtained in addition to the effects (1) to (11) according to the first embodiment. It becomes like this.

  (16) In the cylinder liner 2 of the present embodiment, the coating 5 is formed using a coating agent for mold centrifugal casting. As a result, when forming the coating 5, it is possible to divert the mold centrifugal casting coating agent or its raw material used when the cylinder block 11 is manufactured, so that man-hours and costs can be reduced. become.

(Seventh embodiment)
A seventh embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the film formation mode in the cylinder liner of the first embodiment is changed as described below. The cylinder liner of this embodiment is the same as that of the first embodiment except for the configuration described below.

<Formation of film>
FIG. 26 shows an enlarged structure of the ZC portion of FIG.
In the cylinder liner 2, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27. The film 5 is composed of a low adhesion layer (low adhesion layer 57). Note that the low adhesion agent indicates a liquid material prepared by including a material having low adhesion to the cylinder block 11.

In forming the low adhesion agent layer 57, for example, the following low adhesion agent can be used.
・ Low adhesion agent prepared by mixing graphite, water glass and water.
・ Low adhesion agent prepared by mixing boron nitride and water glass.

<Joint state between cylinder block and liner low temperature part>
FIG. 27 shows a joined state of the cylinder block 11 and the liner low-temperature part 27 (cross-sectional structure of the ZA part in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  About the joining state of the cylinder block 11 and the film 5, the cylinder block 11 and the film 5 are bonded via the gap 5H because the film 5 is formed through a low adhesion agent having low adhesion to the cylinder block 11. ing. Note that when the cylinder block 11 is manufactured, the casting material is solidified in a state where there is a portion where the casting material and the low adhesion agent layer 57 are not sufficiently adhered to each other. A gap 5H is formed between them.

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in such a state, which is described in “[1]“ Linear low temperature portion joined state ”” of the first embodiment (A ) And (B) can be obtained.

<Method for producing film>
In this embodiment, the film 5 is formed by painting and drying the low adhesion agent.
Formation of the film 5 can be performed by the following procedure.
[1] The cylinder liner 2 is preheated by holding the cylinder liner 2 for a predetermined time in a furnace heated to a predetermined temperature.
[2] By immersing the cylinder liner 2 in a container in which the liquid low adhesion agent is stored, the low adhesion agent is coated on the outer peripheral surface 22 of the liner.
[3] After the step [2] is performed, the low adhesion agent is dried by holding the cylinder liner 2 in the furnace of the above [1] for a certain period of time.
[4] The steps [1] to [3] are repeated until the low adhesion agent layer 57 formed by drying has a predetermined thickness.

<Effect of embodiment>
As described above in detail, according to the cylinder liner according to the seventh embodiment, effects according to the effects (1) to (11) of the first embodiment can be obtained.

<Other configuration of the embodiment>
In addition, the said 7th Embodiment can also be implemented as the following forms which changed this suitably, for example.

As the low adhesion agent, for example, the following can be adopted.
(A) A low adhesion agent prepared by mixing graphite and an organic solvent.
(B) A low adhesion agent prepared by mixing graphite and water.
(C) A low adhesion agent mainly composed of boron nitride and an inorganic binder or an organic binder.

(Eighth embodiment)
An eighth embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the film formation mode in the cylinder liner of the first embodiment is changed as described below. The cylinder liner of this embodiment is the same as that of the first embodiment except for the configuration described below.

<Formation of film>
FIG. 26 shows an enlarged structure of the ZC portion of FIG.
In the cylinder liner 2, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27. The film 5 is composed of a metallic paint layer (paint layer 58).

<Joint state between cylinder block and liner low temperature part>
FIG. 27 shows a joined state of the cylinder block 11 and the liner low-temperature part 27 (cross-sectional structure of the ZA part in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  As for the joining state of the cylinder block 11 and the coating 5, the cylinder block 11 and the coating 5 are joined via the gap 5 </ b> H because the coating 5 is formed through a metallic paint having low adhesion to the cylinder block 11. Yes. When the cylinder block 11 is manufactured, the casting material is solidified in a state where there is a portion where the casting material and the coating layer 58 are not sufficiently adhered to each other. Therefore, the gap 5H is formed between the cylinder block 11 and the coating layer 58. Will be formed.

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in such a state, which is described in “[1]“ Linear low temperature portion joined state ”” of the first embodiment (A ) And (B) can be obtained.

<Effect of embodiment>
As described above in detail, according to the cylinder liner according to the eighth embodiment, effects according to the effects (1) to (11) of the first embodiment can be obtained.

(Ninth embodiment)
A ninth embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the film formation mode in the cylinder liner of the first embodiment is changed as described below. The cylinder liner of this embodiment is the same as that of the first embodiment except for the configuration described below.

<Formation of film>
FIG. 26 shows an enlarged structure of the ZC portion of FIG.
In the cylinder liner 2, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27. The film 5 is composed of a heat-resistant resin layer (heat-resistant resin layer 59).

<Joint state between cylinder block and liner low temperature part>
FIG. 27 shows a joined state of the cylinder block 11 and the liner low-temperature part 27 (cross-sectional structure of the ZA part in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  Regarding the joined state between the cylinder block 11 and the film 5, the film 5 is formed through a heat-resistant resin having low adhesion to the cylinder block 11, so that the cylinder block 11 and the film 5 are joined via the gap 5H. Yes. In manufacturing the cylinder block 11, the casting material is solidified in a state where there is a portion where the casting material and the heat-resistant resin layer 59 are not sufficiently adhered to each other. A gap 5H is formed.

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in such a state, which is described in “[1]“ Linear low temperature portion joined state ”” of the first embodiment (A ) And (B) can be obtained.

<Effect of embodiment>
As described above in detail, according to the cylinder liner according to the ninth embodiment, effects equivalent to the effects (1) to (11) of the first embodiment can be obtained.

(10th Embodiment)
A tenth embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the film formation mode in the cylinder liner of the first embodiment is changed as described below. The cylinder liner of this embodiment is the same as that of the first embodiment except for the configuration described below.

<Formation of film>
FIG. 26 shows an enlarged structure of the ZC portion of FIG.
In the cylinder liner 2, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low temperature portion 27. The film 5 includes a layer (chemical conversion treatment layer 50) formed through chemical conversion treatment.

As the chemical conversion treatment layer 50, for example, the following layers can be formed.
・ Phosphate chemical conversion treatment layer.
・ Chemical conversion layer of iron trioxide.

<Joint state between cylinder block and liner low temperature part>
FIG. 27 shows a joined state of the cylinder block 11 and the liner low-temperature part 27 (cross-sectional structure of the ZA part in FIG. 1).

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in a state where the cylinder block 11 and the protrusion 3 are engaged with each other. Further, the cylinder block 11 and the liner low-temperature portion 27 are joined via the film 5.

  About the joining state of the cylinder block 11 and the film 5, the cylinder block 11 and the film 5 are bonded via the gap 5H because the film 5 is formed through the chemical conversion treatment layer having low adhesion to the cylinder block 11. ing. Note that when the cylinder block 11 is manufactured, the casting material is solidified in a state where there is a portion where the casting material and the chemical conversion treatment layer 50 are not sufficiently adhered to each other. A gap 5H is formed.

  In the engine 1, the cylinder block 11 and the liner low temperature portion 27 are joined in such a state, which is described in “[1]“ Linear low temperature portion joined state ”” of the first embodiment (A ) And (B) can be obtained.

  In addition, since the coating 5 is formed through the chemical conversion treatment, a sufficient thickness of the coating 5 is secured at the constricted portion 33 of the protrusion 3. Thereby, since the gap 5H is easily formed around the constricted portion 33 of the cylinder block 11, the heat insulating performance around the constricted portion 33 can be improved.

<Effect of embodiment>
As described above in detail, according to the cylinder liner according to the tenth embodiment, the following effects can be obtained in addition to the effects (1) to (11) according to the first embodiment. It becomes like this.

  (17) In the cylinder liner 2 of the present embodiment, the coating 5 is formed through chemical conversion treatment. Thereby, the heat insulation performance around the constricted portion 33 can be further improved.

(Other embodiments)
In addition, elements that can be changed in common with each of the above embodiments are listed below.
In each of the above embodiments, the selection range of the first area ratio SA and the second area ratio SB is set to the selection range of Table 1, but can be changed as follows.

First area ratio SA: 10% to 30%
Second area ratio SB: 20% to 45%

By adopting such a setting, the liner joint strength and the filling property of the casting material between the protrusions 3 can be further improved.

  In each of the above embodiments, the selection range of the standard protrusion length HP is set to “0.5 mm to 1.0 mm”, but can be changed as follows. That is, the selection range of the standard protrusion length HP can be set to “0.5 mm to 1.5 mm”.

  In each of the above embodiments, the coating 5 is formed on the liner outer peripheral surface 22 of the liner low-temperature portion 27, while the coating 5 is not formed on the liner outer peripheral surface 22 of the liner high-temperature portion 26. It can also be changed. That is, the coating 5 can be formed on the liner outer peripheral surface 22 of the liner low temperature portion 27 and the liner high temperature portion 26. When such a configuration is employed, it is possible to more reliably suppress the occurrence of a location where the cylinder wall temperature TW becomes excessively low.

  In each of the above embodiments, the coating 5 is formed over the entire circumferential direction of the cylinder liner 2, but the formation position of the coating 5 can be changed as follows. That is, it is possible to prevent the coating 5 from being formed on the liner outer peripheral surface 22 between the cylinder bores 15 in the arrangement direction of the cylinders 13. In other words, in the arrangement direction of the cylinders 13, the coating 5 can be formed within a range excluding the liner outer peripheral surface 22 facing the liner outer peripheral surface 22 of the adjacent cylinder liner 2. When such a configuration is adopted, the following effects (a) and (b) can be obtained.

  (A) Since the heat from the adjacent cylinders 13 tends to be trapped between the cylinder bores 15, the cylinder wall temperature TW tends to be higher than the portion other than between the cylinder bores 15 in the circumferential direction of the cylinder 13. Therefore, by adopting the formation mode of the film 5, it is possible to suppress the cylinder wall temperature TW at a location located between the cylinder bores 15 in the circumferential direction of the cylinder 13 from becoming excessively high.

  (B) In the cylinder 13, as described above, the cylinder wall temperature TW varies depending on the position in the circumferential direction, and accordingly, the deformation amount of the cylinder bore 15 also varies in the circumferential direction. Such a difference in the deformation amount of the cylinder bore 15 causes an increase in piston friction, and is one of the factors that deteriorate the fuel consumption rate.

  When the formation mode of the film 5 is adopted, the thermal conductivity of the portion other than between the cylinder bores 15 in the circumferential direction of the cylinder 13 is lowered, while the thermal conductivity between the cylinder bores 15 is the same as that of a normal engine. The difference between the cylinder wall temperature TW at a location other than between the cylinder bores 15 and the cylinder wall temperature TW between the cylinder bores 15 is reduced. Thereby, the difference in the deformation amount of the cylinder bore 15 in the circumferential direction is reduced (the deformation amount is made uniform), so that the fuel consumption rate can be improved through the reduction of the piston friction.

-The manufacturing method of the membrane | film | coat 5 is not restricted to the manufacturing method (thermal spraying, coating, resin coating, and chemical conversion treatment) illustrated in each said embodiment, A suitable manufacturing method is employable.
-In each said embodiment, the formation aspect of the membrane | film | coat 5 can also be changed as follows. That is, the film 5 can be formed using an appropriate material within a range in which at least one of the following conditions (A) and (B) is satisfied.
(A) The thermal conductivity of the film 5 is smaller than the thermal conductivity of the cylinder liner 2.
(B) The thermal conductivity of the film 5 is smaller than the thermal conductivity of the cylinder block 11.

  In each of the above embodiments, the film 5 is formed on the cylinder liner 2 in which the formation state parameter of the protrusion 3 is set within the selection range of Table 1, but any cylinder liner provided with the protrusion 3 is used. The film 5 can also be formed.

  In each of the above embodiments, the film 5 is formed on the cylinder liner 2 provided with the protrusions 3, but the film 5 is formed on the cylinder liner provided with protrusions other than the constricted shape. You can also

  In each of the above embodiments, the film 5 is formed on the cylinder liner 2 provided with the protrusions 3, but the film 5 can also be formed on a cylinder liner not provided with the protrusions.

  In each of the above embodiments, the cylinder liner of the present invention is applied to an aluminum alloy engine. However, for example, the cylinder liner of the present invention can also be applied to a magnesium alloy engine. In short, the cylinder liner of the present invention can be applied to any engine provided with a cylinder liner. Even in such a case, by embodying the present invention in a mode according to each of the above-described embodiments, a function and effect in accordance with the function and effect of each of the above-described embodiments can be achieved.

DESCRIPTION OF SYMBOLS 1 ... Engine, 11 ... Cylinder block, 12 ... Cylinder head, 13 ... Cylinder, 14 ... Cylinder inner wall, 15 ... Cylinder bore.
2 ... Cylinder liner, 21 ... Liner inner peripheral surface, 22 ... Liner outer peripheral surface, 23 ... Liner upper end, 24 ... Liner lower end, 25 ... Liner middle part, 26 ... Liner high temperature part, 27 ... Liner low temperature part, 28 ... Wall temperature boundary.

3 ... Projection, 31 ... Base end portion, 32 ... Tip portion, 32A ... Top surface, 32B ... Maximum tip portion, 33 ... Constricted portion, 33A ... Constricted surface, 34 ... Constricted space.
5 ... coating, 51 ... ceramic sprayed layer, 52 ... iron sprayed layer, 52A ... small sprayed layer, 53A ... first sprayed layer, 53B ... second sprayed layer, 54 ... oxide layer, 55 ... release agent layer, 56 ... coating agent layer, 57 ... low adhesion agent layer, 58 ... paint layer, 59 ... heat-resistant resin layer, 50 ... chemical conversion treatment layer, 5H ... void.

  61 ... Suspension, 61A ... Refractory base material, 61B ... Binder, 61C ... Water, 62 ... Surfactant, 63 ... Coating material, 64 ... Coating layer, 64A ... Bubble, 64B ... Recessed hole, 64C ... Concave hole having a constricted shape, 65 ... mold, 65A ... inner peripheral surface of mold, 66 ... molten metal, 67 ... blast treatment device.

71 ... Test piece for measuring protrusion, 72 ... Single cylinder cylinder block, 73 ... Cylinder, 74 ... Test piece for strength evaluation, 74A ... Liner piece, 74B ... Aluminum piece.
DESCRIPTION OF SYMBOLS 81 ... Three-dimensional laser measuring device, 82 ... Laser beam, 83 ... Test stand, 84 ... Image processing apparatus, 85 ... Contour map, 85A ... 1st contour map, 85B ... 2nd contour map, 86 ... Arm, 87 ... Clamp .

91 ... arc spraying device, 92 ... wire.
SR: radial cross-sectional area, TW: cylinder wall temperature, TP: film thickness, TPmax: maximum thickness, H: measurement height, PA: first reference plane, PB: second reference plane, SA: first area SB ... second area ratio, SD ... standard cross-sectional area, NP ... standard number of protrusions, HP ... standard protrusion length, HL ... contour, RA ... first region, RB ... second region.

Claims (3)

In the cylinder liner for cast-in-hole applied to the cylinder block,
A cylinder liner characterized in that a coating having a lower thermal conductivity than at least one of the cylinder block and the cylinder liner is formed only in a range from an axially intermediate portion to a lower end of the outer peripheral surface of the cylinder liner. The cylinder liner according to claim 1,
A cylinder liner characterized in that the thickness of the coating is increased toward the lower end in the axial direction. The cylinder liner according to claim 1 or 2,
The cylinder liner is characterized in that the coating is not formed on the outer peripheral surface of the cylinder liner corresponding to the space between the cylinder bores of the cylinder block.

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